Structure determination of H2V3O8 by powder X-ray diffraction

A vanadium oxyhydroxide H2V3O8 with a green fibrous shape was hydrothermally synthesized; it was originally formulated as V3O7 · H2O. It has an orthorhombic symmetry: a = 16.9298(2), b = 9.3589(1), c = 3.64432(4), Å, and Z = 4. The structure analysis was performed by the Rietveld method using powder X-ray diffraction data. A structure model for the space group Pnam was found to be compatible with the X-ray data leading to Rp = 0.059 and Rwp = 0.063. The structure is described as a layer structure composed of V3O8 layers which are made up with VO6 octahedra (V(1)O6 and V(2)O6) and VO5 trigonal bipyramids (V(3)O5), where V(3) was assigned to V5+ and V(2) was likely V4+. The arrangement of VO polyhedra resembles to that in β-Na0.33V2O5.